The present invention relates to the control of gas flow.
More particularly, the invention provides a two-part housing for a damper element, typically useful in air-conditioning ducts, the design of the housing providing manufacturing and installation advantages.
Gas flow in furnace chimneys, cooking and water heating appliances used in food preparation, in ventilation vents and air conditioning ducts often require some form of flow control. A simple baffle plate, hinged about its mid point, has been found to operate satisfactorily in most applications. The baffle plate may be controlled by had, be electrically operated but manually controlled, or control and operation can be completely automatic.
Where the baffle plate housing is small it can conveniently be made in one piece, as can be seen for example in the xe2x80x9cHONEYWELLxe2x80x9d automatic furnace vent damper. This unit is intended to reduce room heat losses when the gas furnace is off. The damper has an aluminum cast housing, is available to fit flue diameters between 4xe2x80x3 to 6xe2x80x3 and has a 5 watt motor automatically actuated,
In air conditioning systems ducts are typically larger, and a die to manufacture a complete housing would be large, complex and expensive relative to the number of units being produced.
Current practice is to construct dampers using two flange-like metal housings which are riveted together. The installation technician needs to take this bulky unit to the site where work is to be carried out. Manufacturing costs for the housing are high.
In many countries intense competition prevails between manufacturers, and also between installers of air conditioning systems, wherefore any possible cost reduction of a major component can provide a significant advantage.
In U.S. Pat. No. 4,175,593 Sack discloses plastic cable ducting wherein the duct wall is slit along the length thereof. Opposed to the slit, the wall is weakened to form an integral hinge. The dusting is used to cover an existing laid cable. The duct thus forms a hollow cylinder which has a complete lengthwise split. While the Sack patent is unconnected to air ducts, the principle of axial splitting, as opposed to splitting in a perpendicular direction is demonstrated as an economic method of providing access to the inside of a conduit.
It is therefore one of the objects of the present invention to obviate the disadvantages of prior art gas duct damper housings and to provide a housing split lengthwise, parallel to its axis, which housing can be manufactured without including high die costs.
It is a further object of the present invention to provide a housing which can form a compact package before assembly, and which can be easily and quickly assembled on site without the use of tools.
The present invention achieves the above objects by providing a plastic damper housing for a gas duct particularly useful in air conditioning systems, said housing providing support bearings for damper plate hinge shafts, and comprising an assembly of two identical moldings each shaped substantially as an open-ended half hollow cylinder, each half hollow cylinder being provided along a first axial edge with at least one male interconnection element and on a second opposite edge with at least one corresponding female interconnection element.
In a preferred embodiment of the present invention there is provided a plastic damper housing wherein each said half hollow cylinder is further provided with a guide and retention element for supporting therein a base-plate of an actuating device.
In a most preferred embodiment of the present invention there is provided a motor-powered gas damper for use in combination with an air-conditioning system, said damper being located inside a split plastic damper housing as described above.
Yet further embodiments of the invention will be described hereinafter.
It is well known that in plastic molding, dies to manufacture large components become more expensive than similar dies for a small component, the cost increase and weight increase of the die being more than proportional to size of the molding to be produced therefrom. This results from the need to increase all three dimensions of the die to mold the larger component.
The economics of tooling is also dependent on the number of items to be processed. Thus with regard to plastic castings, a larger number of smaller moldings is far preferable to a smaller number of larger moldings.
By careful design, and by retaining symmetry about the half-length of the component, it has been found possible to produce a half-housing, including rail supports for an electric drive unit, that can be assembled to an identical half-housing when rotated 180 degrees relative to the first unit. This has been achieved even for embodiments provided with a motor support rail on one side.
During storage and transport to the installation site the two half-housings nest together and form a reasonably compact package.
Interconnection of the two half-housings, including the damper element held therebetween can be effected on site without the use of any tool. Time required is about 20 seconds.